CN102426353A - Method for offline acquisition of airborne InSAR (Interferometric Synthetic Aperture Radar) motion error by utilizing high-precision POS (Position and Orientation System) - Google Patents

Abstract

The invention relates to a method for offline acquisition of an airborne InSAR (Interferometric Synthetic Aperture Radar) motion error by utilizing a high-precision POS (Position and Orientation System). The method comprises the steps of acquiring location information of and below quadratic term, of an SINS (Ship's Inertial Navigation System) center by utilizing a combined measurement result of the SINS and a GPS (Global Positioning System) in the high-precision POS; acquiring location information above the quadratic term, of the SINS center by employing a purely inertial measurement result of the SINS; adding the calculated location information of and below the quadratic term to the calculated location information above the quadratic term and compensating a lever arm effect error; calculating high-precision smooth location information of two antenna phase centers of the airborne InSAR; then, subtracting a first-order polynomial fitting result from the high-precision smooth location information; and finally acquiring the motion error of the two antennas of the airborne InSAR. The method provided by the invention has the characteristics of high precision and simplicity for calculation, and can be used for offline calculation of the motion error of the airborne high-precision InSAR in order to realize high-precision offline imaging for the airborne InSAR.

Description

A kind of method of utilizing high precision POS off-line to obtain airborne InSAR kinematic error

Technical field

The present invention relates to a kind ofly to utilize positional accuracy measurement to reach centimetre-sized, attitude measurement accuracy reaches 10, and " (Position and Orientation System POS) obtains the method for airborne InSAR kinematic error to the high precision position attitude measurement system of magnitude.

Background technology

(Synthetic Aperture Radar SAR) is the means of a kind of advanced person's earth observation to airborne synthetic aperture radar.With respect to optics earth observation equipment; Characteristics such as that carried SAR has is round-the-clock, round-the-clock, operating distance are far away; And ground vegetation, artificial camouflage even surface soil layer had certain penetrability, become one of the most representative earth observation means in the world today day by day.Especially airborne high precision InSAR; Can carry out stereo mapping; Having important use in fields such as national basis mapping, survey of territorial resources, geological resource exploration, agriculture agricultural feelings monitoring, disaster monitoring and military surveillances, is the crucial dual-use hi-tech equipment of country.

The ultimate principle of carried SAR imaging requires the machine that carries to do unaccelerated flight, and promptly requiring to contain suffered the making a concerted effort of machine in the synthetic aperture time is zero.But because the influence of factors such as atmospheric turbulence, equipment performance, the machine that carries certainly exists the effect of perturbed force along heading and side direction, and (Anten na Phase Center APC) departs from desirable at the uniform velocity linear translational motion to cause the antenna phase center of carried SAR.Common situation is to carry machine under the control of robot pilot, to swing back and forth around Desired Track, thereby produces kinematic error.This has very important influence to the SAR imaging resolution, when serious even cause SAR to form images.Therefore, in Airborne High-resolution SAR imaging process, must carry out the kinematic error compensation.

The carried SAR kinematic error compensation method will has two kinds, and a kind of auto-focus method that is based on the radar return data, another kind are based on the kinematic error measuring method of POS.At present, mature methods is that auto-focus method combines with POS, utilizes auto-focus method to obtain the low order kinematic error, utilizes POS to obtain the high order kinematic error.But, for airborne InSAR, adopt auto-focus method can destroy interference fringe, make InSAR can't realize the vertical accuracy measurement.Therefore, the kinematic error compensation method will that airborne InSAR can not adopt self-focusing to combine with POS presses for a kind of method that can accurately obtain airborne InSAR kinematic error.

Summary of the invention

Technology of the present invention is dealt with problems and is: the deficiency that overcomes prior art; A kind of method of utilizing high precision POS off-line to obtain airborne InSAR kinematic error is provided; This method has made full use of SINS/GPS multiple measurement and the pure inertia measurement of SINS advantage separately; Improve the precision of kinematic error, for airborne InSAR kinematic error compensation provides an effective way.

Technical solution of the present invention is: a kind of airborne InSAR kinematic error offline computing method based on high precision POS; Utilize that the multiple measurement result of SINS and GPS obtains the secondary at SINS center and a positional information below the secondary among the high precision POS; Utilize the pure inertia measurement result of SINS to obtain the above positional information of secondary at SINS center; With the secondary that calculates and positional information below the secondary and item positional information more than secondary adduction compensation bar arm effect errors mutually; Calculate the level and smooth positional information of high precision of two antenna phase centers of airborne InSAR; Again the level and smooth positional information of high precision is deducted one of which order polynomial fitting result, finally obtain the kinematic error of two antennas of airborne InSAR.

Concrete performing step is following:

(1) under the prerequisite of SINS data that get access to the POS record and gps data; Adopt the method for " forward direction Kalman filtering+back is to level and smooth " that SINS data and the gps data that POS writes down carried out information fusion; Obtain the multiple measurement result at SINS center, comprise position, speed and attitude;

(2) confirm the start time T that airborne InSAR forms images for the i time _I0With concluding time T _I1

(3) at T _I0Constantly, be initial value with the multiple measurement result, start strapdown and resolve program B, to T _I1Constantly finish strapdown and resolve program B, calculate [T _I0, T _I1] the pure inertia measurement result at SINS center in the time period, comprise position, speed and attitude;

(4) with [T _I0, T _I1] the quadratic polynomial match is carried out in the position of multiple measurement in the time period, the quadratic fit result of multiple measurement position is [T _I0, T _I1] secondary and a positional information below the secondary at SINS center in the time period;

(5) with [T _I0, T _I1] the quadratic polynomial match is carried out in pure inertia measurement position in the time period, utilizes pure inertia measurement position to deduct its quadratic fit result again, obtains [T _I0, T _I1] the above positional information of the secondary at SINS center in the time period;

(6), promptly obtain the precise position information at SINS center with more than the secondary at SINS center site error and a secondary and a site error summation below the secondary;

(7) adopt lever arm error between following formula compensation SINS center and two the InSAR antenna phase centers, calculate the level and smooth positional information of high precision of two antenna phase centers of airborne InSAR:

x _i＝x+Δx _i (i＝1，2)

y _i＝y+Δy _i (i＝1，2)

z _i＝z+Δz _i (i＝1，2)

Wherein, x, y, z represent the positional information at SINS center, x _i, y _i, z _iBe the positional information of i InSAR antenna phase center, Δ x _i, Δ y _i, Δ z _iBe the lever arm error of SINS center to i InSAR antenna phase center;

(8) step 7 is obtained the level and smooth positional information of high precision and deduct one of which order polynomial fitting result, obtain the kinematic error of two antennas of airborne InSAR.

Principle of the present invention is: utilize that the multiple measurement result of SINS and GPS obtains the secondary at SINS center and a positional information below the secondary among the high precision POS; Utilize the pure inertia measurement result of SINS to obtain the above positional information of secondary at SINS center; With the secondary that calculates and positional information below the secondary and item positional information more than secondary adduction compensation bar arm effect errors mutually; Calculate the level and smooth positional information of high precision of two antenna phase centers of airborne InSAR; Again the level and smooth positional information of high precision is deducted one of which order polynomial fitting result, finally obtain the kinematic error of two antennas of airborne InSAR.

The present invention's advantage compared with prior art is:

(1) the present invention has given full play to the SINS/GPS multiple measurement absolute precision is high but the pure inertia measurement resultant error accumulation of high order sum of errors SINS is arranged but the characteristics of data smoothing as a result; Through combining of multiple measurement result and pure inertia measurement result; The high precision of airborne InSAR antenna phase center, level and smooth information have been obtained, again through deducting the kinematic error that its fitting result has obtained airborne InSAR antenna phase center.

(2) the present invention has precision height (can reach millimeter level the relative position error), calculates characteristic of simple, can be used for the kinematic error of the airborne high precision InSAR of calculated off-line, to realize the high precision off-line imaging of airborne InSAR.

Description of drawings

Fig. 1 is a kind of airborne InSAR kinematic error offline computing method process flow diagram based on high precision POS of the present invention;

Fig. 2 resolves process flow diagram for the Kalman filtering that relates among the present invention;

Fig. 3 resolves process flow diagram for the pure inertia that relates among the present invention.

Embodiment

As shown in Figure 1, practical implementation of the present invention may further comprise the steps:

1, under the prerequisite of SINS data that get access to the POS record and gps data; Adopt the method for " forward direction Kalman filtering+back is to level and smooth " that SINS data and the gps data that POS writes down carried out information fusion; Obtain the multiple measurement result at SINS center; Comprise position, speed and attitude, the thinking of described " forward direction Kalman filtering+back is to level and smooth " data processing method is: in time T ₀-T _nIn, use the forward direction Kalman filtering and store each estimation and variance battle array constantly (to comprise

P _k, P _{K+1, k}, K _k, Φ _{K+1, k}), after the forward direction Kalman filtering finishes, adopt smoothing equation and obtain level and smooth with whole estimations of storing and the anti-order of variance battle array information

And P _K/n

1. the concrete formula of described forward direction Kalman filtering is following:

● system state equation:

$\stackrel{\·}{X}=\mathrm{FX}+\mathrm{GW}---\left(1\right)$

Wherein, X is a system state vector, and W is the system noise vector, and F is system's transition matrix, and G is the noise transition matrix:

$X={\left[\begin{array}{ccccccccccccccc}{\mathrm{\φ}}_x& {\mathrm{\φ}}_y& {\mathrm{\φ}}_z& {\mathrm{\δv}}_x& {\mathrm{\δv}}_y& {\mathrm{\δv}}_z& \mathrm{\δL}& \mathrm{\δ\λ}& \mathrm{\δh}& {\mathrm{\ϵ}}_x& {\mathrm{\ϵ}}_y& {\mathrm{\ϵ}}_z& {\▿}_x& {\▿}_y& {\▿}_z\end{array}\right]}^T$

$F=\left[\begin{array}{cc}{F}_{\mathrm{INS}}& F_S\\ o_{6\×6}& F_M\end{array}\right],$ $F_S=\left[\begin{array}{cc}{C}_b^n& 0_{3\×3}\\ 0_{3\×3}& C_b^n\\ 0_{3\×3}& 0_{3\×3}\end{array}\right],$ F _M＝[0 _6×15]， $G=\left[\begin{array}{cc}{C}_b^n& 0_{3\×3}\\ 0_{3\×3}& C_b^n\\ 0_{9\×3}& 0_{9\×3}\end{array}\right]$

Wherein, φ _x, φ _yAnd φ _zBe the platform misalignment, δ v _x, δ v _yWith δ v _zBe velocity error, δ L, δ λ and δ h are respectively latitude error, longitude error and height error, ε _x, ε _yAnd ε _zBe gyroscope Random Constant Drift error, Δ _x, Δ _yAnd Δ _zFor accelerometer often is worth biased error, F at random _INSBe the inertia system matrix,

Be system's attitude transition matrix;

● the measurement equation of system

Z＝HX+η(2)

Wherein: Z is a measurement vector, and H is an observing matrix, and η is a measurement noise, and I is a unit matrix:

Z＝[δlδλδh?δv _x?δv _y?δv _z] ^T

$H=\left[\begin{array}{ccc}{0}_{3\×6}& I_{3\×3}& 0_{3\×6}\\ 0_{3\×3}& I_{3\×3}& 0_{3\×9}\end{array}\right]$

● the layout of Kalman filtering rudimentary algorithm, the process flow diagram of this algorithm is as shown in Figure 2:

State one-step prediction equation

${\stackrel{\mathrm{\Λ}}{X}}_{k/k-1}={\mathrm{\φ}}_{k,k-1}{\stackrel{\mathrm{\Λ}}{X}}_{k-1}---\left(3\right)$

Wherein, φ _{K, k-1}Be carved into k system state transition matrix constantly when being respectively k moment system state one-step prediction value, k-1 moment system state valuation, k-1;

The State Estimation accounting equation

${\stackrel{\mathrm{\Λ}}{X}}_k={\stackrel{\mathrm{\Λ}}{X}}_{k/k-1}+K_k(Z_k-H_k{\stackrel{\mathrm{\Λ}}{X}}_{k/k-1})---\left(4\right)$

Wherein,

K _k, Z _k, H _kBe respectively k system state valuation constantly, system-gain matrix, measure vector sum measurement matrix;

Filtering increment equation

$K_k=P_{k/k-1}{H}_k^T{(H_k{P}_{k/k-1}{H}_k^T+R_k)}^{-1}---\left(5\right)$

Wherein, P _K/k-1, R _kThe one-step prediction of etching system covariance matrix, k moment system measurements noise matrix when being respectively k;

One-step prediction square error equation

$P_{k/k-1}={\mathrm{\φ}}_{k,k-1}{P}_{k-1}{\mathrm{\φ}}_{k,k-1}^T+{\mathrm{\Γ}}_{k-1}{Q}_{k-1}{\mathrm{\Γ}}_{k-1}^T---\left(6\right)$

Wherein, P _K-1, Q _K-1, Г _K-1Etching system covariance matrix, k-1 system noise matrix, k-1 system noise driving constantly constantly matrix when being respectively k-1;

Estimate the square error equation

$P_k=(I-K_k{H}_k)P_{k/k-1}{(I-K_k{H}_k)}^T+K_k{R}_k{K}_k^T---\left(7\right)$

Wherein, P _kBe k moment system state covariance matrix;

2. described back to the smoothing formula layout:

${\hat{X}}_{k/n}={\hat{X}}_k+P_k{\mathrm{\φ}}_{k+1,k}^T{P}_{k,k-1}^{-1}({\hat{X}}_{k+1/n}-{\hat{X}}_{k+1,k})---\left(8\right)$

$P_{k/n}=P_k+A_k(P_{k+1/n}-P_{k+1,k})A_k^T---\left(9\right)$

$A_k=P_k{\mathrm{\φ}}_{k+1,k}^T{P}_{k+1,k}^{-1}---\left(10\right)$

Wherein,

P _K/n, P _K+1/nBe respectively and utilize T ₀-T _nThe k that smoothly obtains of all forward direction filtered state estimation value, k+1 etching system covariance matrix when etching system covariance matrix and k+1 when state estimation value, k constantly constantly constantly,

P _k, P _{K+1, k}, P _{K, k-1}, Φ _{K+1, k}Be respectively the k moment state estimation value that adopts the forward direction Kalman filtering to obtain; Be carved into k+1 system state transition matrix constantly, A when the one-step prediction of k+1 moment state one-step prediction value, k moment system state covariance, k+1 moment system state covariance, the one-step prediction of k moment system state covariance, k _kGain matrix when level and smooth.

2, confirm the start time T of the i time imaging of airborne InSAR _I0With concluding time T _I1

3, at T _I0Constantly, be initial value with the multiple measurement result, carry out strapdown and resolve, to T _I1Constantly finish strapdown and resolve, calculate [T _I0, T _I1] the pure inertia measurement result at SINS center in the time period, comprising position, speed and attitude, described strapdown solution formula is:

1. under the earth coordinates of the WGS-84 whole world, the numerical value of the gravity acceleration g of carrier present position is:

$g=9.7803267714\×(1-2\frac{h}{R_{e}h})\×\frac{(1+0.00193185138639{\sin }^{2}L)}{{(1-0.00669437999013{\sin }^{2}L)}^{1/2}}---\left(11\right)$

Wherein, h is a height, R _eBe earth radius, L is a geographic latitude;

2. the computing formula of attitude matrix

is:

$C_n^b=\left[\begin{array}{ccc}\cos \mathrm{\γ}\cos \mathrm{\ψ}-\sin \mathrm{\γ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\γ}\sin \mathrm{\ψ}+\sin \mathrm{\γ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& -\sin \mathrm{\γ}\cos \mathrm{\θ}\\ -\cos \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\θ}\cos \mathrm{\ψ}& \sin \mathrm{\θ}\\ \sin \mathrm{\γ}\cos \mathrm{\ψ}+\cos \mathrm{\γ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& \sin \mathrm{\γ}\sin \mathrm{\ψ}-\cos \mathrm{\γ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& \cos \mathrm{\γ}\cos \mathrm{\θ}\end{array}\right]---\left(12\right)$

Wherein, ψ, θ, γ are respectively course angle, the angle of pitch and roll angle;

3. the computing formula of location matrix

is:

$C_e^n=\left[\begin{array}{ccc}-\sin \mathrm{\λ}& \cos \mathrm{\λ}& 0\\ -\sin L\cos \mathrm{\λ}& -\sin L\sin \mathrm{\λ}& \cos L\\ \cos L\cos \mathrm{\λ}& \cos L\sin \mathrm{\λ}& \sin L\end{array}\right]---\left(13\right)$

Wherein, L and λ are respectively geographic latitude and longitude;

4. hypercomplex number q computing formula does

$q=\left[\begin{array}{c}{q}_0\\ q_1\\ q_2\\ q_3\end{array}\right]=\left[\begin{array}{c}\cos \frac{\mathrm{\ψ}}{2}\cos \frac{\mathrm{\θ}}{2}\cos \frac{\mathrm{\γ}}{2}-\sin \frac{\mathrm{\ψ}}{2}\sin \frac{\mathrm{\θ}}{2}\sin \frac{\mathrm{\γ}}{2}\\ \cos \frac{\mathrm{\ψ}}{2}\sin \frac{\mathrm{\θ}}{2}\cos \frac{\mathrm{\γ}}{2}-\sin \frac{\mathrm{\ψ}}{2}\cos \frac{\mathrm{\θ}}{2}\sin \frac{\mathrm{\γ}}{2}\\ \cos \frac{\mathrm{\ψ}}{2}\cos \frac{\mathrm{\θ}}{2}\sin \frac{\mathrm{\γ}}{2}+\sin \frac{\mathrm{\ψ}}{2}\sin \frac{\mathrm{\θ}}{2}\cos \frac{\mathrm{\γ}}{2}\\ \cos \frac{\mathrm{\ψ}}{2}\sin \frac{\mathrm{\θ}}{2}\sin \frac{\mathrm{\γ}}{2}+\sin \frac{\mathrm{\ψ}}{2}\cos \frac{\mathrm{\θ}}{2}\cos \frac{\mathrm{\γ}}{2}\end{array}\right]---\left(14\right)$

5. use the angle increment method to calculate the posture renewal matrix, the quadravalence computing formula is:

$q(n+1)=\{(1-\frac{{\left(\mathrm{\Δ}{\mathrm{\θ}}_0\right)}^2}{8}+\frac{{\left({\mathrm{\Δ\θ}}_0\right)}^4}{384})I+(\frac{1}{2}-{\left(\frac{{\mathrm{\Δ\θ}}_0}{48}\right)}^2\left(\mathrm{\Δ\θ}\right))\}q\left(n\right)---\left(15\right)$

Wherein,

$\mathrm{\Δ\θ}=\left[\begin{array}{cccc}0& -{\mathrm{\Δ\θ}}_x& -{\mathrm{\Δ\θ}}_y& -\mathrm{\Δ}{\mathrm{\θ}}_z\\ {\mathrm{\Δ\θ}}_x& 0& {\mathrm{\Δ\θ}}_z& -{\mathrm{\Δ\θ}}_y\\ {\mathrm{\Δ\θ}}_y& -{\mathrm{\Δ\θ}}_z& 0& {\mathrm{\Δ\θ}}_x\\ {\mathrm{\Δ\θ}}_z& {\mathrm{\Δ\θ}}_y& -{\mathrm{\Δ\θ}}_x& 0\end{array}\right]$

${\mathrm{\Δ\θ}}_0^2={\mathrm{\Δ\θ}}_x^2+{\mathrm{\Δ\θ}}_y^2+{\mathrm{\Δ\θ}}_z^2$

6. the speed calculation formula is:

$\left[\begin{array}{c}{\stackrel{\·}{v}}_x^n\\ {\stackrel{\·}{v}}_y^n\\ {\stackrel{\·}{v}}_z^n\end{array}\right]=\left[\begin{array}{c}{a}_{\mathrm{ibx}}^n\\ a_{\mathrm{iby}}^n\\ a_{\mathrm{ibz}}^n\end{array}\right]+\left[\begin{array}{ccc}0& {2\mathrm{\ω}}_{\mathrm{iez}}^n+{\mathrm{\ω}}_{\mathrm{enz}}^n& -({2\mathrm{\ω}}_{\mathrm{iey}}^n+{\mathrm{\ω}}_{\mathrm{eny}}^n)\\ -(2{\mathrm{\ω}}_{\mathrm{iez}}^n++{\mathrm{\ω}}_{\mathrm{enz}}^n)& 0& {2\mathrm{\ω}}_{\mathrm{iex}}^n+{\mathrm{\ω}}_{\mathrm{enx}}^n\\ 2{\mathrm{\ω}}_{\mathrm{iey}}^n+{\mathrm{\ω}}_{\mathrm{eny}}^n& -({2\mathrm{\ω}}_{\mathrm{iex}}^n+{\mathrm{\ω}}_{\mathrm{enx}}^n)& 0\end{array}\right]\left[\begin{array}{c}{v}_x^n\\ v_y^n\\ v_z^n\end{array}\right]-\left[\begin{array}{c}0\\ 0\\ g\end{array}\right]---\left(16\right)$

Wherein,

and

is the relative acceleration under the geographical coordinate system in sky, northeast;

and

is the non-gravitational acceleration under the geographical coordinate system in sky, northeast; and

is the speed under the geographical coordinate system in sky, northeast;

and

is the rotational-angular velocity of the earth projection of day coordinate system northeastward, and

and

are for by navigation coordinate being the angular velocity of rotation projection of day coordinate system northeastward of the relative earth;

⑦ navigation position matrix

or Update is calculated as:

${\stackrel{\·}{C}}_n^e=C_n^e{\mathrm{\Ω}}_{\mathrm{en}}^n---\left(17\right)$

Wherein:

${\mathrm{\Ω}}_{\mathrm{en}}^n=\left[\begin{array}{ccc}0& -{\mathrm{\ω}}_{\mathrm{enz}}^n& {\mathrm{\ω}}_{\mathrm{eny}}^n\\ {\mathrm{\ω}}_{\mathrm{enz}}^0& 0& -{\mathrm{\ω}}_{\mathrm{enx}}^n\\ -{\mathrm{\ω}}_{\mathrm{eny}}^n& {\mathrm{\ω}}_{\mathrm{enx}}^n& 0\end{array}\right]---\left(18\right)$

4, with [T _I0, T _I1] the quadratic polynomial match is carried out in the position of multiple measurement in the time period, the quadratic fit result of multiple measurement position is [T _I0, T _I1] secondary and a positional information (comprising Lonz2, Latz2, Altz2) below the secondary at SINS center in the time period, concrete steps are:

1. adopt Matlab software to read in [T _I0, T _I1] position data of multiple measurement in the time period, and with longitude, latitude, highly, the time uses 4 n * 1 dimensional vector Lonz, Latz, Altz and T to represent that wherein n is [T respectively _I0, T _I1] number of time multiple measurement position data;

2. utilize the polyfit function in the Matlab software to obtain [T _I0, T _I1] interior multiple measurement position data of time period and the quadratic function of time, promptly obtaining each item coefficient in this quadratic function, specific instructions is following:

Aloz＝polyfit(T，Lonz，2)；

Alaz＝polyfit(T，Latz，2)；

Atz＝polyfit(T，Altz，2)；

Wherein, three vectorial Aloz, Alaz and Atz represent each item coefficient of the time quadratic function of longitude, latitude and height respectively;

3. utilization last goes on foot each item coefficient of the quadratic polynomial that obtains, and adopts the polyval function in the Matlab software to obtain [T _I0, T _I1] the quadratic fit result of multiple measurement longitude, latitude and height in the time period, represent that with Lonz2, Latz2 and Altz2 specific instructions is following respectively:

Lonz2＝polyval(Aloz，T)；

Latz2＝polyval(Alaz，T)；

Altz2＝polyval(Atz，T)；

5, with [T _I0, T _I1] the quadratic polynomial match is carried out in pure inertia measurement position in the time period, utilizes pure inertia measurement position to deduct its quadratic fit result again, obtains [T _I0, T _I1] the above positional information of the secondary at SINS center in the time period, concrete steps are:

1. adopt Matlab software to read in [T _I0, T _I1] position data of pure inertia measurement in the time period, and with longitude, latitude, highly, the time uses 4 n * 1 dimensional vector Loni, Lati, Alti and T to represent that wherein n is [T respectively _I0, T _I1] number of pure inertia measurement position data of time;

2. utilize the polyfit function in the Matlab software to obtain [T _I0, T _I1] quadratic function of pure inertia measurement position data in the time period (longitude, latitude and height) and time, promptly obtain each item coefficient in this quadratic function, represent that with Aloi, Alai and Ati specific instructions is following respectively:

Aloi＝polyfit(T，Loni，2)；

Alai＝polyfit(T，Lati，2)；

Ati＝polyfit(T，Alti，2)；

3. utilization last goes on foot each item coefficient of the quadratic polynomial that obtains, and adopts the polyval function in the Matlab software to obtain [T _I0, T _I1] the quadratic fit result of pure inertia measurement position data in the time period, i.e. Loni2, Lati2 and Alti2, specific instructions is following:

Loni2＝polyval(Aloi，T)；

Lati2＝polyval(Alai，T)；

Alti2＝polyval(Ati，T)；

4. utilize pure inertia measurement positional information and quadratic fit result thereof, the former deducts secondary above positional information Loni3, Lati3 and Alti3 that the latter obtains pure inertia measurement, and concrete formula is following:

Loni3＝Loni-Loni2；

Lati3＝Lati-Lati2；

Alti3＝Alti-Alti2；

Wherein, Lon3, Lat3 and Alt3 are the above longitude of SINS center secondary, latitude and the height that utilizes pure inertia measurement data to obtain; Loni2, Lati2 and Alti2 are SINS center secondary and a longitude below the secondary, latitude and the height that utilizes pure inertia measurement data to obtain, and Loni, Lati and Alti are longitude, latitude and the height that pure inertia measurement obtains.

6, with more than the secondary at SINS center positional information and a secondary and a positional information summation below the secondary, promptly obtain precise position information Lon, Lat and the Alt at SINS center, concrete formula is following:

Lon＝Lonz2+Loni3；

Lat＝Latz2+Lati3；

Alt＝Altz2+Alti3；

Wherein, Lon, Lat and Alt are longitude, latitude and the elevation information at the SINS center that finally obtains; Lon2, Lat2 and Alt2 are SINS center secondary and a longitude below the secondary, latitude and the height that utilizes the multiple measurement data to obtain, and Lon3, Lat3 and Alt3 are the above longitude of SINS center secondary, latitude and the height that utilizes pure inertia measurement data to obtain.

7, adopt lever arm error between following formula compensation SINS center and two the InSAR antenna phase centers, calculate the level and smooth positional information of high precision of two antenna phase centers of airborne InSAR:

x _i＝x+Δx _i (i＝1，2)(1)

y _i＝y+Δy _i (i＝1，2)(2)

z _i＝z+Δz _i (i＝1，2)(3)

Wherein, x, y, z represent the positional information at SINS center, x _i, y _i, z _iBe the positional information of i InSAR antenna phase center, Δ x _i, Δ y _i, Δ z _iBe the lever arm error of SINS center to i InSAR antenna phase center;

8, step 7 is obtained the level and smooth positional information of high precision and deduct one of which order polynomial fitting result, obtain the kinematic error of two antennas of airborne InSAR, concrete formula is following:

1. utilize the polyfit function in the Matlab software to obtain [T _I0, T _I1] interior level and smooth positional information of high precision (comprising longitude Lon, latitude Lat and height A lt) of time period and the linear function of time, promptly obtain each item coefficient in this linear function, represent that with Alo1, Ala1 and At1 specific instructions is following respectively:

Alo1＝polyfit(T，Lon，1)；

Ala1＝polyfit(T，Lat，1)；

At1＝polyfit(T，Alt，1)；

2. utilization last goes on foot each item coefficient of the quadratic polynomial that obtains, and adopts the polyval function in the Matlab software to obtain [T _I0, T _I1] the once fitting result of the level and smooth positional information of high precision in the time period (longitude, latitude and height), i.e. Lon1, Lat1 and Alt1, specific instructions is following:

Lon1＝polyval(Alo1，T)；

Lat1＝polyval(Ala1，T)；

Alt1＝polyval(At1，T)；

3. utilize level and smooth positional information of high precision and once fitting result thereof, the former deducts kinematic error Δ Lon, Δ Lat and Δ Alti that the latter obtains two antennas of I nSAR, and concrete formula is following:

ΔLon＝Lon-Lon1；

ΔLat＝Lat-Lat1；

ΔAlt＝Alt-Alt1；

Wherein, Δ Lon, Δ Lat and Δ Alti represent longitude error, latitude error and the height error of two antennas of InSAR respectively; Lon, Lat and Alti are longitude, latitude and the height of two antennas of InSAR of smoothly obtaining of high precision, and Lon1, Lat1 and Alti1 are longitude, latitude and the height that utilizes Lon, Lat and Alti to carry out once fitting to obtain.

The content of not doing in the instructions of the present invention to describe in detail belongs to this area professional and technical personnel's known prior art.

Claims (2)

1. method of utilizing high precision POS off-line to obtain airborne InSAR kinematic error is characterized in that performing step is following:

(1) under the prerequisite of SINS data that get access to the POS record and gps data; Adopt the method for " forward direction Kalman filtering+back is to level and smooth " that SINS data and the gps data that POS writes down carried out information fusion; Obtain the multiple measurement result at SINS center, comprise position, speed and attitude;

(2) confirm the start time T that airborne InSAR forms images for the i time _I0With concluding time T _I1

(3) at T _I0Constantly, be initial value with the multiple measurement result, carry out strapdown and resolve, to T _I1Constantly finish strapdown and resolve, calculate [T _I0, T _I1] the pure inertia measurement result at SINS center in the time period, comprise position, speed and attitude;

(4) with [T _I0, T _I1] the quadratic polynomial match is carried out in the position of multiple measurement in the time period, the quadratic fit result of multiple measurement position is [T _I0, T _I1] secondary and a positional information below the secondary at SINS center in the time period;

(5) with [T _I0, T _I1] the quadratic polynomial match is carried out in pure inertia measurement position in the time period, utilizes pure inertia measurement position to deduct its quadratic fit result again, obtains [T _I0, T _I1] the above positional information of the secondary at SINS center in the time period;

(6), promptly obtain the precise position information at SINS center with more than the secondary at SINS center site error and a secondary and a site error summation below the secondary;

(7) the lever arm error between compensation SINS center and two the InSAR antenna phase centers calculates the level and smooth positional information of high precision of two antenna phase centers of airborne InSAR;

(8) step (7) is obtained the level and smooth positional information of high precision and deduct one of which order polynomial fitting result, obtain the kinematic error of two antennas of airborne InSAR.

2. a kind of method of utilizing high precision POS off-line to obtain airborne InSAR kinematic error according to claim 1 is characterized in that: the formula of the lever arm error in the said step (7) between compensation SINS center and two the InSAR antenna phase centers is following:

x _i＝x+Δx _i

y _i＝y+Δy _i

z _i＝z+Δz _i

Wherein, i=1,2; X, y, z represent the positional information at SINS center; x _i, y _i, z _iIt is the positional information of i I nSAR antenna phase center; Δ x _i, Δ y _i, Δ z _iBe the lever arm error of SINS center to i InSAR antenna phase center.

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